Re: Boarding and rafting to stranger's boats.
I don't think it is a big deal at all. It was a public dock, if you were not comfortable with someone rafting up you could have found a spot to anchor and dingy in to the dock. Most public docks can get quite busy. It is a good plan to put out fenders (perhaps even with a board across them to give you better protection). My thought is what do you do to the rafted boat when you want to leave? You obviously can't just let the lines go. I imagine they are supposed to have a radio with them if everyone leaves the boat. Just another reason to avoid the situation. It is considered best practice if crossing the boat to do it on the Bow, as it invades the privacy the least. I read that somewhere, but I don't remember where.
Now if they went down below while crossing your boat then I would have an issue.